It looks like, by default, rustc adds "-Wl,-Bdynamic" "-ldl" "-lrt" "-lpthread" "-lgcc_s" "-lc" "-lm" "-lrt" "-lpthread" "-lutil" "-lutil" to the linker command line on Linux. I'm trying to find out where these come from. It looks like some of those might come from link directives in std, or in std's build.rs file. But in particular, I'm not finding where -lutil comes from.